Reinsurance is a financial market that trades in the risk of unpredictable and devastating disasters - such as Hurricane Katrina, the Tohoku earthquake and tsunami, and the terrorist attacks on the World Trade Centre. Such disasters are increasing in both frequency and severity, with the cost of their losses mounting rapidly. Reinsurance insures insurance companies, enabling them to pay claims arising from these losses. It is thus a market mechanism that is a critical part of the social and economic safety net, helping to pick up the pieces after disasters. Yet, how is the risk of such...